Any way to schedule Spotlight indexing?

Not a contradiction because the data written to the index is usually quite small compared to the size of the file being written to disk at the same time. For example, with images - when you save the file to disk, it may be a 5MB file. When written to disk, it may trigger an associated write of 10KB of metadata.

For documents with a lot of text, there would be a scan of the file as Spotlight pulls out the unique terms in the file to add to the content index, but even this will be quite small compared to the actual file. So, the extra overhead specifically due to Spotlight normally shouldn't be noticed. Essentially it adds a relatively insignificant secondary write to the larger original disk write that you initiated when you saved or copied the file.

If you are noticing a lot of extra activity with iCal or when surfing maybe there is something else going on. With iCal and Safari open, mds and mdimport are sitting quietly at 0% CPU and not adding much of anything to disk writes except when first opened for me.

As for using Spotless, et al, people have found that they are unable to get Spotlight to find anything even after they try to turn off the effects of Spotless. This may be due to them trying a cocktail of methods to alter Spotlight behavior and then not knowing how to reverse all the steps.
Just in the the 2.5 years that I've been on Tiger and been dealing with Spotlight, it seems to work the best when you just let it work and not try so hard to fix it.

For more info on how Spotlight works, take a look at the Spotlight Technical Brief

After the initial indexing, Spotlight indexes as files are written. Whenever a file is saved, it is passed through the mdimport server which determines which Spotlight Importer is associated with the particular file type and gleans the indexable data from the file as it's on it's way to the hard disk.

That is the key to Spotlight's functionality - if it didn't index on-the-fly for each file, it would have a bigger resource footprint.

Now, personally, I think you should generally avoid using Spotless or any other method (except maybe the Privacy pane) to alter Spotlight's behavior because it seems to potentially cause issues when trying to turn it back on. You really shouldn't notice too much activity specifically attributable to Spotlight. To check, keep an eye on mdimport and mds in ActivityMonitor.

There's no way to do this... Spotlight does real-time indexing and there's no way to make it do it on a schedule. You could turn it off and use the command-line 'locate' command to find stuff... it runs on a schedule 😉

Aside from initial indexing... Spotlight has minimal overhead.